U.S. Pat. No. 3,437,401 describes a light box for animating selected parts of a picture, whereby use is made of a rotating polarizing disc and a light-interrupting foil, which is provided with several picture line patterns impressed on those parts of the foil that constitute the part to be animated. Said picture lines have been impressed on the light-interrupting foil by means of a die or a punch. For the projection use is made in principle of one or more light sources, a polarizing disc rotating in front of said light sources and a picture carrier located in front of said polarizing disc, whereby the picture carrier is locally provided with parts acting as an analyzer. Said parts acting as an analyzer may be made by providing certain tension lines according to a certain pattern, yet oriented in varying directions in the various locations. A suitable selection of the material of the picture carrier or the foil will make it possible, by impressing tension lines, to obtain a polarizing effect, on the basis of the properties of the foil material itself. Furthermore it is possible to provide unevenness, oriented in certain directions, on a foil of a suitable material and to provide an ink layer containing polarizing crystals on said foil. The orientation of said polarizing crystals will then adapt itself to the orientation of the unevenness. With such a pretreated foil it is also possible to provide a possibly colorless layer containing polarizing crystals before or after providing the colored printing inks.
This known method is, in particular, suitable for producing a large number of identical light-interrupting foils. A large number of intermediate steps are necessary, however, in order to provide the parts oriented in various directions of the picture in which a certain polarizing effect is to be effected. Thus, it is not unusual to orientate the tension lines and the like in at least nine different directions; it is more common, however, to orientate said tension lines at twenty-four different angles. For each individual direction a separate mask, such as e.g., known from lithography, is to be used.
The drawback of such a method is that it is costly, time-consuming and quite laborious, because of the great accuracy that is required, while a very high percentage of rejects will still have to be reckoned with.
The use of a die for providing local deformations at various orientations is, inter alia, described in U.S. Pat. No. 3,650,625. From this U.S. patent, it is clear how complicated and expensive (approximately $7,000) the manufacture of a die described therein is. A further drawback of this known manufacturing system is that the accuracy thereof is not satisfactory in practice, while further additional devices are die-rollers and pressing-rollers have to be used.
Laser Praxis, Oct. 1990, Munchen Carl Hansen Verlag, pp. 125 through 128 (M. Meyer et al.) describes a system to put numbers, letters and barcodes on organic and anorganic materials while using a laser. However, this document does not refer to the creation of small tension lines, thereby orientating the molecules in a direction perpendicular thereto, and ordering the various wavelengths of light so that an impression of movement is effected using a polarisator and an analysator.
Patent Abstracts of Japan, Vol. 11, No. 68 (p. 553), Feb. 28, 1987, and JP-A-61 231531, Oct. 15, 1986 describe a method for manipulating a video film, for example, with the aid of mirrors. A picture of a film is provided with another background, for example, and this manipulation is recorded on film or videotape.